net: ethernet: ti: cpts: fix overflow check period

The CPTS drivers uses 8sec period for overflow checking with
assumption that CPTS retclk will not exceed 500MHz. But that's not
true on some TI platforms (Kesytone 2). As result, it is possible that
CPTS counter will overflow more than once between two readings.

Hence, fix it by selecting overflow check period dynamically as
max_sec_before_overflow/2, where
 max_sec_before_overflow = max_counter_val / rftclk_freq.

Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/ti/cpts.c b/drivers/net/ethernet/ti/cpts.c
index ebd413a1cf5663e3e8fc7a3aed2fd5fdaaaa7a0f..0c0d48e5bea4ee709764a3cecb22e2490ec0694a 100644 (file)
--- a/drivers/net/ethernet/ti/cpts.c
+++ b/drivers/net/ethernet/ti/cpts.c
@@ -245,7 +245,7 @@ static void cpts_overflow_check(struct work_struct *work)
 
        cpts_ptp_gettime(&cpts->info, &ts);
        pr_debug("cpts overflow check at %lld.%09lu\n", ts.tv_sec, ts.tv_nsec);
-       schedule_delayed_work(&cpts->overflow_work, CPTS_OVERFLOW_PERIOD);
+       schedule_delayed_work(&cpts->overflow_work, cpts->ov_check_period);
 }
 
 static int cpts_match(struct sk_buff *skb, unsigned int ptp_class,
@@ -378,8 +378,7 @@ int cpts_register(struct cpts *cpts)
        }
        cpts->phc_index = ptp_clock_index(cpts->clock);
 
-       schedule_delayed_work(&cpts->overflow_work, CPTS_OVERFLOW_PERIOD);
-
+       schedule_delayed_work(&cpts->overflow_work, cpts->ov_check_period);
        return 0;
 
 err_ptp:
@@ -423,6 +422,11 @@ static void cpts_calc_mult_shift(struct cpts *cpts)
        if (maxsec > 10)
                maxsec = 10;
 
+       /* Calc overflow check period (maxsec / 2) */
+       cpts->ov_check_period = (HZ * maxsec) / 2;
+       dev_info(cpts->dev, "cpts: overflow check period %lu (jiffies)\n",
+                cpts->ov_check_period);
+
        if (cpts->cc.mult || cpts->cc.shift)
                return;
 

diff --git a/drivers/net/ethernet/ti/cpts.h b/drivers/net/ethernet/ti/cpts.h
index 5da23af7a9a60b74d344a1fd190daf90df461246..c96eca2b1b46033a67198c0bd346b8dbc4929fed 100644 (file)
--- a/drivers/net/ethernet/ti/cpts.h
+++ b/drivers/net/ethernet/ti/cpts.h
@@ -97,9 +97,6 @@ enum {
        CPTS_EV_TX,   /* Ethernet Transmit Event */
 };
 
-/* This covers any input clock up to about 500 MHz. */
-#define CPTS_OVERFLOW_PERIOD (HZ * 8)
-
 #define CPTS_FIFO_DEPTH 16
 #define CPTS_MAX_EVENTS 32
 
@@ -127,6 +124,7 @@ struct cpts {
        struct list_head events;
        struct list_head pool;
        struct cpts_event pool_data[CPTS_MAX_EVENTS];
+       unsigned long ov_check_period;
 };
 
 void cpts_rx_timestamp(struct cpts *cpts, struct sk_buff *skb);